The invention relates generally to the structure and operation of a spring barrel module, which is installed in a small space.
The size of portable electronic equipment in particular is being constantly reduced. This makes great demands, e.g. on the usability and durability of the various mechanical components in the equipment.
The physical components of electronic equipment are constructed to be as simple as possible, suitable for mass production and easy to install on automated assembly lines. The components of equipment should be designed so that tolerance variations occurring in the components do not obstruct the installation or lessen the performance of the equipment.
Examples of small electronic equipment containing mechanically movable components are mobile terminals, CD stations, and CD players. The smallest mobile terminals are physically so tiny, that when the loudspeaker is held to the ear, the microphone does not reach all the way to the user""s mouth without special arrangements. Mobile terminals of this kind can be enlarged with the aid of a telescope structure or with some other enlargement implementation, such as a collapsible structure. The force needed for the enlargement can be supplied by the user, or obtained from a spring or a motor, for example.
A mobile terminal that includes a body part and a grip part is described in the applicant""s earlier patent application FI20001008, which has not been published by the filing date of the present application.
A relatively large portion of the body part is located within the sleeve-like grip part. The grip part is mounted for longitudinal slideable movement between a retractable position and an extended position. A spring barrel, within which a spring and a bidirectional damper are combined, is installed in the body part of the mobile terminal. When the mobile terminal is in the idle position, the body part is within the sleeve-like part, and the spring is compressed, that is, the spring is in its stressed state. When the fastening lock of the grip part and the body part is released, the stored force of the spring pushes out the body part of the mobile terminal from the grip part into the extended or operative position. The damper slows down the mechanical movement of the body part in relation to the grip part. More specifically, the mechanical movement of the body part is controlled by the bi-directional damper, which absorbs a part of the spring force to prevent the body part from jumping out suddenly and noisily into the enlarged position. After the mobile terminal has been used, the spring is reset, by the body part being pushed down manually into the grip part.
Typically there is very little space in small equipment. Valuable space is saved by a solution whereby both the spring and the damper are installed within the same housing.
However, it is a drawback in the described solution that the damper does not function in the normal manner at low or freezing temperatures (below 0xc2x0 C.). This is mainly due to the behaviour of the damping oil in the damper housing. The oil solidifies and thus causes a high torque and stress to the mechanical components of the spring barrel. This results in a serious malfunction: the opening mechanism of the mobile terminal works very slowly if at all.
In addition, when the damper does not work or works very slowly, there is always the risk that the user will try to open or close the equipment by force. In the worst case such behaviour may break the mechanical components of the spring barrel.
The invention especially concerns a spring barrel module which is installed in a small space in small-sized equipment, such as a mobile terminal, and which is easy to install and economically advantageous to manufacture. It is an objective of the present invention to implement the structure of the spring barrel module so that the energy stored in the spring of the spring barrel module is adapted to convert into a linear or rotary movement, so that a certain small piece of equipment, e.g. a mobile terminal, which is designed to open, will open in a controlled manner and smoothly. It is especially important that the opening force remains as uniform as possible during the entire movement.
It is also an object of the present invention to make the manual closing operation easy and smooth for the user and in addition to protect the mechanism when the user uses force to either open or close the equipment.
This objective is achieved in the manner described in the independent claim. Advantageous embodiments of the invention are defined in the dependent claims.
The spring barrel module includes a combined spring and a damper. This solution takes less space than a separate spring and damper. The spring is preferably a clock spring. The energy stored in the spring is converted by a rotary spring shaft and then by a belt or some other such means into a linear or rotary motion. In an advantageous embodiment the damper is unidirectional, i.e. it works in one direction only. This unidirectional damper is implemented by a clutch means which connects the damper plate to the spring shaft causing slowed down rotation when the tightened spring is released. Correspondingly, the clutch loosens the connection between the damper plate and the spring shaft when the spring is tightened in order to make the manual closure easier.
Should the ambient temperature drop below a certain temperature level depending on the damping fluid used e.g. below xe2x88x9210xc2x0 C. degrees, the damper will not dampen the rotation at all.
When the electronic equipment is closed, the spring in the spring barrel module is in its tightened state. When the spring is released, the spring force is converted by a spring shaft which is adapted to rotate by some means such as a belt into a linear or rotary motion, so that that component of the electronic equipment which is adapted to move will open in a controlled and smooth manner. When the component adapted to move is closed, e.g. by pushing it manually, the spring will reset.
Depending on the application, more than one spring barrel module can be installed in one piece of equipment. The place where the spring barrel is installed depends on how large a space there is in the equipment for installation of the spring barrel module. Another decisive factor is how long or wide a movement is desired for the component adapted to move.
The unidirectional feature of the damper improves both usability and durability. In addition, breakage of the mechanical components of the spring barrel is prevented by an overload clutch, which means that the spring barrel module will tolerate even relatively rough handling of the equipment.
An advantageous way of passing on the force obtained from the spring is by adapting the spring to rotate the spring shaft and to pass on the force by way of a toothed rack and gear to that component of the electronic equipment which is adapted to be movable.
Another advantageous way of passing on the force obtained from the spring is by adapting the spring to rotate the spring shaft and to pass on the force by way of a threaded screw to that component of the electronic equipment which is adapted to be movable.
Yet another advantageous way of passing on the force obtained from the spring is by adapting the spring to rotate the spring shaft and to pass on the force through a wheel adapted to be rotary to that component of the electronic equipment which is adapted to be movable.